1. Field of the Invention
The present invention relates to a jet propulsion boat which moves ahead or astern by jetting water sucked from an opening in a boat""s bottom in a backward direction.
2. Description of Background Art
A known jet propulsion boat of a type operated in a manner similar to that for a motorcycle is configured as follows. A driver sitting astride a seat holds the steering handlebar with both hands to operate the boat to go ahead by actuating an accelerator lever at the right end of the steering handlebar. The operator makes the boat go astern or slow down by operating an operating lever at the left end of the steering handle.
A jet propulsion boat of this type has been proposed, for example, in Japanese Patent Laid-open No. Hei 6-156379. The technique disclosed in this document will be briefly described with reference to FIG. 8.
FIG. 8 is a view illustrating the above-described prior art jet propulsion boat. Referring to FIG. 8, the jet propulsion boat designated by reference numeral 100 includes an operating lever 104 mounted on a left grip 102 of a steering handlebar 101; an accelerator lever 105 mounted on a right grip 103 of the steering handlebar 101; a water jetting nozzle 106 mounted at a stem of the jet propulsion boat 100; and a going-astern bucket 108 mounted to the nozzle 106.
An operational procedure for making the jet propulsion boat 100 go astern will be described below.
First, the operating lever 104 is operated in the direction shown by an arrow xe2x80x9caxe2x80x9d to move the bucket 108 in the direction shown by an arrow xe2x80x9cbxe2x80x9d up to a position facing to the outlet of the nozzle 106. Then, the accelerator lever 105 is operated in the direction shown by an arrow xe2x80x9ccxe2x80x9d while operating the lever 104, to increase the engine speed.
As the engine speed is increased, an impeller (not shown) is rotated at a high speed, to jet water backward from the nozzle 106. At this time, the direction of the water thus jetted is reversed as shown by an arrow xe2x80x9cdxe2x80x9d by means of the bucket 108. In this way, since the water is jetted forward of the jet propulsion boat 100, the jet propulsion boat 100 goes astern.
The prior art jet propulsion boat, however, has the following problem: namely, in the going-astern mode, a driver requires two operations, that is, the operation of the left operating lever 104 with the left hand and the operation of the accelerator lever 105 with the right hand. Since the driver must simultaneously perform the two-operations with both hands, he must shoulder a relatively large burden. In this regard, it has been desired to develop a jet propulsion boat excellent in operability.
An object of the present invention is to provide a technique capable of improving the operability of a jet propulsion boat.
To solve the above-described problem, according to the present invention, there is provided a jet propulsion boat which moves ahead, in a forward mode, by jetting backward water sucked from an opening in a boat""s bottom through a nozzle, and which goes astern or slows down, in a going-asten/slowing-down mode, by shifting a water reversing cup to a position facing to the outlet of the nozzle and reversing the water jetting direction by means of the cup, the jet propulsion boat including: a transmission mechanism for transmitting a force to drive the water reversing cup; an operating piece for pushing/withdrawing the transmission mechanism; an operating force measuring means for measuring an operating force applied to the operating piece, the operating force measuring means being provided on the transmission mechanism or the operating piece; and a propulsion force control means for controlling a water jetting force on the basis of the operating force measured by the operating force measuring means.
With this configuration, the water jetting force can be controlled on the basis of the operating force by operating the operating piece to shift the water reversing cup to the position facing to the outlet of the nozzle and further increasing the operating force applied to the operating piece.
Accordingly, two-stage operations, that is, the operation to shift the water reversing cup to the position facing to the outlet of the nozzle and the operation to control the water jetting force can be performed by operating only one operating piece. As a result, the going-astern operation or the slowing-down operation of the jet propulsion boat can be performed by one hand or one foot.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.